Electrochromic system with coupled RED-OX system and special anions

ABSTRACT

This invention relates to an electrochromic system containing at least one oxidizable substance RED 1  and at least one reducible substance OX 2  linked covalently by a bridge that are suitable for use in electrochromic devices.

The present invention relates to an electrochromic system, to anelectrochromic fluid comprising this electrochromic system, and to anelectrochromic device comprising this electrochromic fluid.

Electrochromic devices comprising an electrochromic system are alreadyknown.

The electrochromic system of such devices customarily includes pairs ofredox substances—redox couples—dissolved in an inert solvent.Additionally, conductive salts, light stabilizers and substances whichinfluence the viscosity may be present.

The redox couple used comprises one reducible and one oxidizablesubstance each. Both are colourless or have only a weak coloration.Under the influence of an electrical voltage the one substance isreduced and the other oxidized, with at least one becoming coloured inthe process. After the voltage is switched off, the two original redoxsubstances are formed once more, which is accompanied by thedisappearance or fading of the colour.

U.S. Pat. No. 4,902,108 discloses that suitable such redox couples arethose in which the reducible substance has at least two chemicallyreversible reduction waves in the cyclic voltammogram and the oxidizablesubstance, correspondingly, has at least two chemically reversibleoxidation waves.

Electrochromic devices can find multivarious applications. For example,they may take the form of a rearview car mirror which when travelling atnight can be darkened by applying a voltage, thus preventing the driverbeing dazzled by headlights of other vehicles (cf. e.g. U.S. Pat. Nos.3,280,701, 4,902,108, EP-A-0 435 689). Such devices may also be employedin window panes or car sunroofs where, following application of avoltage, they provide shade from the sunlight. Finally, it is possibleto use such devices to construct a display device for the graphicrepresentation of information in the form of letters, numbers andsymbols.

Electrochromic devices normally consist of a pair of glass or plasticplates, one being mirrored in the case of a car mirror. One side ofthese plates is coated with a transparent, electroconductive layer, e.g.indium tin oxide (ITO). These plates are then used to construct a cell:to this end their facing, electroconductively coated side is attached,preferably by means of adhesive bonding, to an annular or rectangularsealing ring. The sealing ring establishes a uniform distance betweenthe plates of, for example, from 0.1 to 0.5 mm. This cell is thenfilled, via an aperture, with an electrochromic solution and thentightly sealed. By way of the ITO layer it is possible to contact thetwo plates separately.

The electrochromic systems known from the prior art comprise redoxcouples which following the reduction and oxidation, respectively, formcoloured free radicals, cationic free radicals or anionic free radicalsthat are chemically reactive. As known, for example, from Topics inCurrent Chemistry, Vol. 92, pp. 1-44 (1980) such (ionic) free radicalsmay be sensitive to electrophiles or nucleophiles or else to freeradicals. In order, therefore, to achieve a high level of stability inan electrochromic device comprising an electrochromic system of thiskind—a system which is intended to withstand several thousand switchingcycles—it is necessary to ensure that the solvent used is absolutelyfree from electrophiles, e.g. protons, nucleophiles and oxygen. It mustalso be ensured that such reactive species are not formed byelectrochemical processes taking place at the electrodes duringoperation of the electrochromic device.

The back-reaction to RED₁ and OX₂ that is formulated in the aboveequation also takes place continuously away from the electrodes withinthe volume of the solution while the electrochromic device is inoperation. Owing to the above-described hazards of degradation reactionsof the (ionic) free radicals by electrophiles, nucleophiles or freeradicals it is important, for the long-term stability of the display,that the back-reaction in accordance with the above equation is able totake place as rapidly as possible and without side reactions.

A frequent observation in such electrochromic devices is a separation,known as segregation, of the coloured species OX₁ and RED 2, leading tothe development in the device of coloured spots or stripes. Segregationof this kind is observed, for example, when the device is not positionedhorizontally. Current flow over a prolonged period may also lead to suchsegregation. Since many of the abovementioned uses of suchelectrochromic devices, for example in the case of car rearview mirrors,window panes or display devices, operate with the device preferably in aperpendicular or near-perpendicular position and in some cases overprolonged periods of time as well, such segregation leads to seriousproblems.

It has now been found that by coupling RED₁ and OX₂ via a covalentchemical bond, and through the presence of specific anions in theelectrochromic solution, it is possible to suppress to a large extent orcompletely eliminate such segregation.

The present invention accordingly relates to an electrochromic systemcomprising at least one oxidizable substance RED₁ which releaseselectrons at an anode, and at least one reducible substance OX₂ whichaccepts electrons at a cathode and in so doing undergo transition from aweakly coloured or colourless form into a coloured form OX₁ and RED₂,respectively, accompanied by an increase in the absorbance in thevisible region of the spectrum, the weakly coloured or colourless formbeing restored after charge equalization, characterized in that at leastone of the substances RED₁ and OX₂ that are present are linkedcovalently to one another via a bridge and in that at least one aniontype X⁻ is present which a) has a molar mass >200 g/mol, preferably >250g/mol and/or b) has a cagelike structure.

Cagelike structure means closed cages as well as such structures derivedfrom closed cages by removing 1 to 3 atoms of the cagelike structure(nestlike structure).

At least one of the transitions induced by oxidation or reduction,RED₁≈OX₁ or OX₂≈RED₂, respectively, is associated with an increase inabsorbance in the visible region of the spectrum.

The reduction and oxidation processes in the electrochromic system ofthe invention generally take place by electrons being accepted orreleased at a cathode or anode, respectively, a potential difference offrom 0.3 to 3 V preferably obtaining between the electrodes. After theelectrical potential has been switched off, charge equalization takesplace—in general spontaneously—between the substances RED₂ and OX₁,accompanied by disappearance or fading of the colour. Such chargeequalization also takes place even while the current is flowing in theinterior of the electrolyte volume.

The electrochromic system of the invention preferably comprises at leastone electrochromic substance of the formula (I)

YB—Z_(a)B—Y_(b)_(c)B—Z  (I),

in which

Y and Z independently of one another represent a radical OX₂ or RED₁,subject to the proviso that at least one Y represents OX₂ and at leastone Z represents RED₁,

 where

OX₂ represents the radical of a reversibly electrochemically reducibleredox system, and

RED₁ represents the radical of a reversibly electrochemically oxidizableredox system,

B represents a bridge member

c represents an integer from 0 to 5, and

a and b independently of one another represent an integer from 0 to 5,preferably an integer from 0 to 3.

The electrochromic system preferably comprises at least oneelectrochromic substance of the formula (I) in which

Y represents OX₂ and Z represents RED₁ and Y and Z alternate in theirsequence.

With particular preference, the electrochromic system of the inventioncomprises at least one electrochromic substance of the formula

OX₂—B—RED₁  (Ia),

 OX₂—B—RED₁—B—OX₂  (Ib),

RED₁—B—OX₂—B—RED₁  (Ic),

or

OX₂—(B—RED₁—B—OX₂)_(d)—B—RED₁  (Id),

in which

OX₂, RED₁ and B have the meaning indicated above and

d represents an integer from 1 to 5.

The electrochromic system of the invention preferably comprises at leastone anion type X⁻ which a) has a molar mass >200 g/mol, preferably >250g/mol and/or b) has a cagelike structure, where X⁻ is the counterion ofOX₂ and/or is a constituent of an inert conductive salt.

Anions with cagelike structure means especially such anions, which arederived from carbaboranes, with very particular preferencedicarba-nido-undecarborates and dicarba-closo-dodecarborates.

Where OX₂ has no positive charge the anion type X⁻ that is present inaccordance with the invention is a constituent of an inert conductivesalt.

The anion type X⁻ present in the electrochromic system of the inventionmay suitably be, in particular:

C₁₀- to C₂₅-alkanesulphonate, preferably C₁₃- to C₂₅-alkanesulphonate,C₃- to C₁₈-perfluoroalkanesulphonate, preferably C₅- toC₁₈-perfluoroalkanesulphonate, C₁₃- to C₂₅-alkanoate, benzenesulphonatesubstituted by nitro, C₄- to C₂₅-alkyl, perfluoro-C₁- to C₈-alkyl, C₁-to C₁₂-alkoxycarbonyl or dichloro, naphthalene- or biphenylsulphonateeach of which is unsubstituted or substituted by nitro, cyano, hydroxyl,C₁- to C₂₅-alkyl, C₁- to C₁₂-alkoxy, amino, C₁- to C₁₂-alkoxycarbonyl orchloro, benzene-, naphthalene- or biphenyldisulphonate each of which isunsubstituted or substituted by nitro, cyano, hydroxyl, C₁- toC₂₅-alkyl, C₁- to C₁₂-alkoxy, C₁- to C₁₂-alkoxycarbonyl or chloro,benzoate substituted by dinitro, C₆- to C₂₅-alkyl, C₄- toC₁₂-alkoxycarbonyl, benzoyl, chlorobenzoyl or toluoyl, or the anion ofnaphthalenedicarboxylic acid, diphenyl ether disulphonate,tetraphenyl-borate, cyanotriphenylborate, tetra-C₃- to C₂₀-alkoxyborate,tetraphenoxyborate, 7,8- or 7,9-dicarba-nido-undecaborate(1-) or (2-),each of which is unsubstituted or substituted on the B and/or C atoms byone or two C₁- to C₁₂-alkyl or phenyl groups,dodecahydrodicarbadodecaborate(2-) or B—C₁- toC₁₂-alkyl-C-phenyl-dode-cahydrodicarbadodecaborate(1-).

With very particular preference, the electrochromic system of theinvention comprises at least one electrochromic substance of theformulae (Ia)-(Id)

in which

OX₂ represents the radical of a cathodically reducible substance whichin its cyclic voltammogram, recorded in an inert solvent at roomtemperature, exhibits at least two chemically reversible reductionwaves, the first of these reduction waves leading to an increase in theabsorbance at at least one wavelength in the visible region of theelectromagnetic spectrum,

RED₁ represents the radical of an anodically reversibly oxidizablesubstance which in its cyclic voltammogram, recorded in an inert solventat room temperature, exhibits at least two chemically reversibleoxidation waves, the first of these oxidation waves leading to anincrease in the absorbance at at least one wavelength in the visibleregion of the electromagnetic spectrum, and

B represents a bridge.

Particular preference is given to an electrochromic system of theinvention which comprises at least one substance of the formula(Ia)-(Id) in which

OX₂ represents a radical of the formula

 where

R² to R⁵, R⁸, R⁹, R¹⁶ to R¹⁹ independently of one another denote C₁- toC₁₈-alkyl, C₂- to C₁₂-alkenyl, C₃- to C₇-cycloalkyl, C₇- to C₁₅-aralkylor C₆ to C₁₀-aryl, or

R⁴ and R⁵ or R⁸ and R9 together form a —(CH₂)₂—or —(CH₂)₃— bridge,

R⁶, R⁷ and R²² to R²⁵ independently of one another denote hydrogen, C₁-to C₄-alkyl, C₁- to C₄-alkoxy, halogen, cyano, nitro or C₁- toC₄-alkoxycarbonyl, or

R²² and R²³ and/or R²⁴ and R²⁵ form a —CH═CH—CH═CH— bridge,

R¹⁰ and R¹¹, R¹² and R¹³, R¹⁴ and R¹⁵ independently of one anotherdenote hydrogen or in pairs denote a —(CH₂)₂—, —(CH₂)₃—or —CH═CH—bridge,

R²⁰ and R²¹ independently of one another denote O, N—CN, C(CN)₂ or N—C₆-to C₁₀-aryl,

R²⁶ denotes hydrogen, C₁- to C₄-alkyl, C₁- to C₄-alkoxy, halogen, cyano,nitro, C₁- to C₄-alkoxycarbonyl or C₆- to C₁₀-aryl,

R⁶⁹ to R⁷⁴ independently of one another denote hydrogen or C₁-C₆-alkyl,or

R⁶⁹; R¹² and/or R⁷⁰; R¹³ form a —CH═CH—CH═CH— bridge,

E¹ and E² independently of one another denote O, S, NR¹ or C(CH₃)₂, or

E¹ and E² —N—(CH₂)₂—N— bridge,

R¹ denotes C₁- to C₁₈-alkyl, C₂- to C₁₂-alkenyl, C₄- to C₇-cycloalkyl,C₇- to C₁₅-aralkyl, C₆- to C₁₀-aryl,

Z¹ denotes a direct bond, —CH═CH—, —C(CH₃)═CH—, —C(CN)═CH—, —CCl═CCl—,—C(OH)═CH—, —CCl═CH—, —C≡C—, —CH═N—N═CH—, —C(CH₃)═N—N═C(CH₃)- or—CCl═N—N═CCl—,

Z² denotes —(CH₂)_(r)— or —CH₂—C₆H₄—CH₂—,

r denotes an integer from 1 to 10,

X⁻ represents an anion which is redox-inert under the conditions andwhich a) has a molar mass >200 g/mol, preferably >250 g/mol and/or b)has a cagelike structure,

where the bond to the bridge B is via one of the radicals R²-R¹⁹,R²²-R²⁷ or, if E¹ or E² represents NR¹, is via R¹, and the radicalsmentioned in that case represent a direct bond,

RED₁ represents one of the following radicals

 in which

R²⁸ to R³¹, R³⁴, R³⁵, R³⁸, R³⁹, R⁴⁶, R⁵³ and Rs⁵⁴ independently of oneanother denote C₁- to C₁₈-alkyl, C₂- to C₁₂-alkenyl, C₃- toC₇-cycloalkyl, C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl, and R⁴⁶, R⁵³ andR⁵⁴ additionally denote hydrogen,

R³², R³³, R³⁶, R³⁷, R⁴⁰, R⁴¹, R⁴² to R⁴⁵, R⁴⁷, R⁴⁸, R⁴⁹ to R⁵² and R⁵⁵to R⁵⁷ independently of one another denote hydrogen, C₁- to C₄-alkyl,C₁- to C₄-alkoxy, halogen, cyano, nitro, C₁- to C₄-alkoxycarbonyl or C₆-to C₁₀-aryl and R⁵⁷ and R⁵⁸ additionally denote an optionallybenzo-fused aromatic or quasi-aromatic five- or six-memberedheterocyclic ring and R⁴⁸ additionally denotes NR⁷⁵R⁷⁶,

R⁴⁹ and R⁵⁰ and/or R⁵¹ and R⁵² form a —(CH₂)₃—, —(CH₂)₄—, —(CH₂)₅—or—CH═CH—CH═CH— bridge,

Z³ denotes a direct bond, a —CH═CH— or —N═N— bridge,

═Z⁴═ denotes a direct double bond, a ═CH—CH═ or ═N—N═ bridge,

E³ to E⁵, E¹⁰and E¹¹ independently of one another denote O, S, NR⁵⁹ orC(CH₃)₂, and E⁵ additionally denotes C═O or SO₂, or

E³ and E⁴ independently of one another denote —CH═CH—,

E⁶ to E⁹ independently of one another denote S, Se or NR⁵⁹,

R⁵⁹, R⁷⁵ and R⁷⁶ independently of one another denote C₁- to C₁₂-alkyl,C₂- to C₈-alkenyl, C₃- to C₇-cycloalkyl, C₇- to C₁₅-aralkyl or C₆- toC₁₀-aryl, and R⁷⁵ additionally denotes hydrogen, or

R⁷⁵ and R⁷⁶ in the definition of NR⁷⁵R⁷⁶ form, together with the N atomto which they are attached, a five- or six-membered, saturated ringwhich can contain further heteroatoms,

R⁶¹ to R⁶⁸ independently of one another denote hydrogen, C₁- toC₆-alkyl, C₁- to C₄-alkoxy, cyano, C₁- to C₄-alkoxycarbonyl or C₆- toC₁₀-aryl, or

R⁶¹; R⁶² and R⁶⁷; R⁶⁸ independently of one another, together form a—(CH₂)₃—, —(CH₂)₄— or —CH═CH—CH═CH— bridge,

v denotes an integer between 0 and 10,

the bond to the bridge B being via one of the radicals R²⁸-R⁵⁸, R⁶¹,R⁶², R⁶⁷, R⁶⁸ or, if one of the radicals E³-E¹¹ represents NR⁵⁹, is viaR⁵⁹ and the abovementioned radicals in that case represent a directbond, and

B represents a bridge of the formula —(CH₂)_(n)— or —[Y¹ _(s)(CH₂)_(m)—Y²]_(o)—(CH₂)_(p)—Y³ _(q)—, each of which is unsubstituted orsubstituted by C₁- to C₄-alkoxy, halogen or phenyl,

Y¹ to Y³ independently of one another represent O, S, NR⁶⁰, COO, CONH,NHCONH, cyclopentanedlyl, cyclohexanediyl, phenylene or naphthylene,

R⁶⁰ denotes C₁- to C₆-alkyl, C₂- to C₆-alkenyl, C₄- to C₇-cycloalkyl,C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl,

n denotes an integer from 1 to 12,

m and p independently of one another denote an integer from 0 to 8,

o denotes an integer from 0 to 6, and

q and s independently of one another denote 0 or 1,

and, if OX₂ has no positive charge, there is at least one conductivesalt present which comprises the abovementioned anion X⁻.

Very particular preference is given to an electrochromic system of theinvention which comprises at least one substance of the formula(Ia)-(Id)

in which

OX₂ represents a radical of the formula (II), (III), (IV) or (V)

 where

R², R³, R⁴, R⁵, R⁸ and R⁹ independently of one another represent C₁- toC₁₂-alkyl, C₂- to C₈-alkenyl, C₅- to C₇-cycloalkyl, C₇- to C₁₅-aralkylor C₆- to C₁₀-aryl,

R⁶ and R⁷ independently of one another represent hydrogen, methyl,ethyl, methoxy, fluoro, chloro, bromo, cyano, nitro, methoxycarbonyl orethoxycarbonyl,

R¹⁰, R¹¹; R¹², R¹³ and R¹⁴, R¹⁵ independently of one another representhydrogen or, if Z¹ denotes a direct bond, in each case togetherrepresent a —(CH₂)₂—, —(CH₂)₃— or —CH═CH— bridge,

or

R⁴, R⁵ and R⁸, R⁹ independently of one another in pairs togetherrepresent a —(CH₂)₂— or —(CH₂)₃— bridge if Z¹ denotes a direct bond,

R⁶⁹ to R⁷⁴ independently of one another denote hydrogen or C₁-C₄-alkyl,

E¹ and E² are identical and represent O, S, NR¹ or C(CH₃)₂ or togetherform an —N—(CH₂)₂—N— bridge,

R¹ represents C₁- to C₁₂-alkyl, C₂- to C₄-alkenyl, C₅- to C₇-cycloalkyl,C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl,

Z¹ represents a direct bond, —CH═CH—, —C(CH₃)═CH—, —C(CN)═CH—, —C≡C— or—CH═N—N═CH—,

Z² represents —(CH)_(r)— or —CH₂—C₆H₄—CH₂—,

r represents an integer between 1 and 6,

X⁻ represents C₁₀- to C₂₅-alkanesulphonate, preferably C₁₃- toC₂₅-alkanesulphonate, C₃- to C₁₈-perfluoroalkanesulphonate, preferablyC₅- to C₁₈-perfluoroalkanesulphonate, C₁₃- to C₂₅-alkanoate,benzenesulphonate substituted by nitro, C₄- to C₂₅-alkyl, perfluoro-C₁-to C₈-alkyl, C₁- to C₁₂-alkoxycarbonyl or dichloro, naphthalene- orbiphenylsulphonate each of which is unsubstituted or substituted bynitro, cyano, hydroxyl, C₁- to C₂₅-alkyl, C₁- to C₁₂-alkoxy, amino, C₁-to C₁₂-alkoxycarbonyl or chloro, benzene-, naphthalene- orbiphenyldisulphonate each of which is unsubstituted or substituted bynitro, cyano, hydroxyl, C₁- to C₂₅-alkyl, C₁- to C₁₂-alkoxy, C₁- toC₁₂-alkoxycarbonyl or chloro, benzoate substituted by dinitro, C₆- toC₂₅-alkyl, C₄- to C₁₂-alkoxycarbonyl, benzoyl, chlorobenzoyl or toluoyl,or the anion of naphthalenedicarboxylic acid, diphenyl etherdisulphonate, tetraphenylborate, cyanotriphenylborate, tetra-C₃- toC₂₀-alkoxyborate, tetraphenoxyborate, 7,8- or7,9-dicarba-nido-undecaborate(1-) or (2-), each of which isunsubstituted or substituted on the B and/or C atoms by one or two C₁-to C₁₂-alkyl or phenyl groups, dodecahydrodicarbadodecaborate(2-) orB—C₁- to C₁₂-alkyl-C-phenyl-dodecahydrodicarbadodecaborate(1-), where inthe case of polyvalent anions such as naphthalenedisulphonate X⁻represents one equivalent of this anion,

where the bond to the bridge B is via one of the radicals R²-R¹¹ or, ifE¹ or E² represents NR¹, is via R¹, and the abovementioned radicals inthat case represent a direct bond,

RED₁ represents a radical of the formula (X), (XI), (XII), (XIII),(XVI), (XVII), (XVIII) or (XX)

where

R²⁸ to R³¹ R³⁴, R³⁵, R³⁸, R³⁹, R⁴⁶, R⁵³ and R⁵⁴ independently of oneanother denote C₁- to C₁₂-alkyl, C₂- to C₈-alkenyl, C₅- toC₇-cycloalkyl, C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl and

R⁴⁶, R⁵³ and R⁵⁴ additionally denote hydrogen,

R³² R³³ R³⁶ R³⁷, R⁴⁰, R⁴¹, R⁴⁷ to R⁵², R⁵⁵ and R⁵⁶ inependently of oneanother denote hydrogen, methyl, ethyl, methoxy, ethoxy, fluoro, chloro,bromo, cyano, nitro, methoxycarbonyl, ethoxycarbonyl or phenyl, and

R⁵⁷ and R⁵⁸ additionally denote 2- or 4-pyridyl, and

R⁴⁸ additionally denotes NR⁷⁵R⁷⁶,

Z³ denotes a direct bond, a —CH═CH— or —N═N— bridge,

═Z⁴═ denotes a direct double bond, a ═CH—CH═ or ═N—N═ bridge,

E³ to E⁵, E¹⁰ and E¹¹, independently of one another denote O, S, NR⁵⁹ orC(CH₃)₂, but E³ and E⁴ have the same meaning,

E⁶ to E⁹ are identical to one another and denote S, Se or NR^(59,) and

E⁵ additionally denotes C═O,

E⁶ represents NR^(59,) where R⁵⁹ denotes a direct bond to the bridge B,and

E⁷ to E⁹ possess the meaning indicated above, but need not be identicalto one another,

R⁵⁹, R⁷⁵ and R⁷⁶ independently of one another denote C₁- to C₁₂-alkyl,C₂- to C₈-alkenyl, C₅- to C₇-cycloalkyl, C₇- to C₁₅-aralkyl or C₆- toC₁₀-aryl, and R⁷⁵ additionally denotes hydrogen, or

R⁷⁵ and R⁷⁶ in the definition NR⁷⁵R⁷⁶ denote, together with the N atomto which they are attached, pyrrolidino, piperidino or morpholino,

R⁶¹, R⁶² and R⁶⁷, R⁶⁸ independently of one another represent hydrogen,C₁- to C₄-alkyl, methoxycarbonyl, ethoxycarbonyl or phenyl, or in pairstogether represent a —(CH₂)₃— or —(CH₂)₄— bridge,

R⁶³ to R⁶⁶ represent hydrogen, and

v represents an integer from 1 to 6,

where the bond to the bridge B is via one of the radicals R²⁸-R⁴¹,R⁴⁶-R⁵⁶, R⁶¹, R⁶², R⁶⁷, R⁶⁸ or, if one of the radicals E³-E¹¹ representsNR⁵⁹, is via R⁵⁹, and the abovementioned radicals in that case representa direct bond,

B represents a bridge of the formulae —(CH₂)_(n)—,—(CH₂)_(m)—O—(CH₂)_(p)—, —(CH)_(m)—NR⁶⁰—(CH₂)_(p)—,—(CH₂)_(m)—C₆H₄—(CH₂)_(p)—, —[O—(CH₂)_(p)]_(o)—O—,—[NR⁶⁰—(CH₂)_(p)]_(o)—NR⁶⁰—, —[C₆H₄—(CH₂)_(p)]_(o)—C₆H₄—,—(CH₂)_(m)—OCO—C₆H₄—COO—(CH₂)_(p)——(CH₂)_(m)—NHCO—C₆H₄—CONH—(CH₂)_(p)—,—(CH₂)_(m)—NHCONH—C₆H₄NHCONH—(CH₂)_(p)—,—(CH₂)_(m)—OCO—(CH₂)_(t)—COO—(CH₂)—,—(CH₂)_(m)—NHCO—(CH₂)_(t)—CONH—(CH)_(p)—,—(CH₂)_(m)—NHCONH—(CH₂)_(t)—NHCONH—(CH₂)_(p)—,

R⁶⁰ represents methyl, ethyl, benzyl or phenyl,

n represents an integer from 1 to 10,

m and p independently of one another represent an integer from 0 to 4,

o represents an integer from 0 to 2, and

t represents an integer from 1 to 6.

Especial preference is given to an electrochromic system of theinvention which comprises at least one substance of the formula(Ia)-(Id)

in which

OX₂ represents a radical of the formula (II), (IV) or (V)

in which

R², R⁴ and R⁸ represent a direct bond to the bridge B,

R³, R⁵ and R⁹ independently of one another represent methyl, ethyl,propyl, butyl, pentyl, hexyl, heptyl, octyl, benzyl or phenyl, or in thecase of the formula Ic or Id likewise represent a direct bond to thebridge B,

R⁶ and R⁷ are identical and represent hydrogen, methyl, methoxy, chloro,cyano or methoxycarbonyl,

R¹⁰, R¹¹; R¹², R¹³ and R¹⁴, R¹⁵ independently of one another representhydrogen or, if Z¹ denotes a direct bond, represent, in each case inpairs together, a —CH═CH— bridge,

R⁶⁹ to R⁷² are identical and denote hydrogen, methyl or ethyl,

R⁷³ and R⁷⁴ denote hydrogen,

E¹ and E² are identical and represent O or S,

Z¹ represents a direct bond or —CH═CH—,

X⁻ represents C₁₅- to C₂₂-alkanesulphonate, C₅- toC₁₂-perfluoroalkanesulphonate, nitrobenzenesulphonate,dinitrobenzenesulphonate, mono- or bis-C₄- toC₁₂-alkylbenzenesulphonate, dichlorobenzenesulphonate,naphthalenesulphonate, nitronaphthalenesulphonate,dinitronaphthalenesulphonate, mono- or bis-C₃- toC₁₂-alkylnaphthalenesulphonate, hydroxynaphthalenesulphonate,aminonaphthalenesulphonate, biphenyl-sulphonate, benzenedisulphonate,nitrobenzenedisulphonate, C₄- to C₁₂-alkylbenzenedisulphonate,naphthalenedisulphonate, nitronaphthalenedisulphonate, C₄- toC₁₂-alkylnaphthalenedisulphonate, biphenyldisulphonate, dinitrobenzoate,mono- or bis-C₈- to C₁₂-alkylbenzoate, C₆- toC₁₂-alkoxycarbonylbenzoate, benzylbenzoate, toluoylbenzoate, the anionof naphthalenedicarboxylic acid, cyanotriphenylborate, tetra-C₃- toC₁₂-alkoxyborate, tetraphenoxyborate, 7,8- or7,9-dicarba-nido-undecaborate(1-) or (2-) each of which is unsubstitutedor substituted on the B and/or C atoms by one or two methyl, ethyl,butyl or phenyl groups, dodecahydrodicarbadodecaborate(2-) orB-methyl-C-phenyl-dodecahydro-dicarbadodecaborate(1-), where in the caseof polyvalent anions such as naphthalenedisulphonate X⁻ represents oneequivalent of this anion,

RED₁ represents a radical of the formula (X), (XII), (XIII), (XVI) or(XVII),

R²⁸, R³⁴, R³⁸, R⁴⁶ and R⁴⁹ represent a direct bond to the bridge B,

R²⁹ to R³¹, R³⁵ and R³⁹ independently of one another represent methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, benzyl or phenyl,or, in the case of the formula Ib or Id, R³⁰, R³⁵ and R³⁹ likewiserepresent the direct bond to the bridge B,

R³², R⁴⁷ and R⁴⁸ represent hydrogen,

R³⁶, R³⁷, R⁴⁰, R⁴¹ and R⁵⁰ to R⁵² independently of one another representhydrogen, methyl, methoxy, chloro, cyano, methoxycarbonyl or phenyl, or,in the case of the formula lb or Id, R⁵¹ likewise represents a directbond to the bridge B,

Z³ represents a direct bond, a —CH═CH— or —N═N— bridge,

═Z⁴═ represents a direct double bond, a ═CH—CH═ or ═N—N═ bridge,

E³ to E⁵ independently of one another represent O, S or NR⁵⁹, but E³ andE⁴ have the same meaning,

E⁶ to E⁹ are identical to one another and represent S, Se or NR⁵⁹,

R⁵⁹ represents methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, benzyl or phenyl, or, in the case of the formula XVI in Ib or Id,likewise represents a direct bond to the bridge B,

B represents a bridge of the formulae —(CH₂)_(n)—,—(CH₂)_(m)—O—(CH₂)_(p)—, —(CH₂)_(m)—NR⁶⁰—(CH₂)_(p)—,—(CH₂)_(m)—C₆H₄—(CH₂)_(p)—, —O—(CH₂)_(p)—O—, —NR⁶⁰—(CH₂)_(p)—NR⁶⁰—,—(CH₂)_(m)—OCO—C₆H₄—COO—(CH₂)_(p)—,—(CH₂)_(m)—NHCO—C₆H₄—CONH—(CH₂)_(p)—,—(CH₂)_(m)—NHCONH—C₆H₄—NHCONH—(CH₂)_(p)—,—(CH₂)_(m)—OCO—(CH₂)_(t)—COO—(CH₂)_(p)—,—(CH₂)_(m)—NHCO—(CH₂)_(t)—CONH—(CH₂)_(p)—,—(CH₂)_(m)—NHCONH—(CH₂)_(t)—NHCONH—(CH₂)_(p)—,

R⁶⁰ represents methyl,

n represents an integer from 1 to 10,

m and p are identical and represent an integer from 0 to 2, and

t represents an integer from 1 to 6.

Very particular preference is given to an electrochromic system of theinvention which comprises at least one substance of the formula (Ia)corresponding to one of the formulae

or at least one substance of the formula (Ib) corresponding to one ofthe formulae

or at least one substance of the formula (Ic) corresponding to one ofthe formulae

in which

R³, R⁵, R³⁵ and R³⁹ independently of one another represent methyl,ethyl, propyl, butyl, pentyl, hexyl or benzyl,

R⁶, R⁷ and R³⁶, R³⁷ in pairs are identical and represent hydrogen,methyl, methoxy, chloro, cyano or methoxycarbonyl,

R¹² and R¹³ represent hydrogen or, if Z¹ denotes a direct bond, togetherrepresent a —-CH═CH— bridge,

R⁶⁹ to R⁷² are identical and represent hydrogen or methyl,

E¹ and E² are identical and represent O or S,

Z¹ represents a direct bond or —CH═CH—,

R³², R⁴⁷ and R⁴⁸ represent hydrogen,

E³ to E⁵ independently of one another represent O, S or NR⁵⁹, but E³ andE⁴ are identical,

R²⁹ to R³¹ and and R⁵⁹ independently of one another represent methyl,ethyl, propyl, butyl, pentyl, hexyl or benzyl, where R²⁹ to R³¹ arepreferably identical,

R⁴⁰ and R⁴¹ are identical and represent hydrogen, methyl, ethyl, propyl,butyl or phenyl,

Z³ represents a direct bond, —CH═CH— or —N═N—,

R⁵⁰ to R⁵² independently of one another represent hydrogen, methyl,methoxy, chloro, cyano, methoxycarbonyl, ethoxycarbonyl or phenyl, butare preferably identical,

E⁶ to E⁹ are identical to one another and represent S, Se or NR⁵⁹,

Z⁴ represents a direct double bond, a ═CH—CH═ or ═N—N═ bridge,

m represents an integer from 1 to 5,

u represents 0 or 1, and

X⁻ represents C₁₅- to C₂₀-alkanesulphonate, C₅- toC₈-perfluoroalkanesulphonate, mono- or dibutylbenzenesulphonate, mono-or di-tert-butylbenzenesulphonate, octylbenzenesulphonate,dodecylbenzenesulphonate, naphthalenesulphonate, biphenylsulphonate,nitrobenzenedisulphonate, naphthalenedisulphonate,dibutylnaphthalenesulphonate, biphenyldisulphonate, benzoylbenzoate,cyanotriphenylborate, tetra-C₃- to C₈-alkoxyborate, tetraphenoxyborate,7,8- or 7,9-dicarba-nido-undecaborate(1-) or (2-) ordodecahydro-dicarbadodecaborate(2-), where in the case of polyvalentanions such as naphthalenedisulphonate X⁻ represents one equivalent ofthis anion.

In the abovementioned definitions of substituents alkyl radicals,including modified versions such as alkoxy or aralkyl radicals, forexample, are preferably those having 1 to 12 C atoms, especially having1 to 8 C atoms, unless indicated otherwise. They can be straight-chainor branched and can if desired carry further substituents such as, forexample, C₁- to C₄-alkoxy, fluoro, chloro, hydroxyl, cyano, C₁- toC₄-alkoxycarbonyl or COOH.

Cycloalkyl radicals are preferably those having 3 to 7 C atoms,especially 5 or 6 C atoms.

Alkenyl radicals are preferably those having 2 to 8 C atoms, especially2 to 4 C atoms.

Aryl radicals, including those in aralkyl radicals, are preferablyphenyl or naphthyl radicals, especially phenyl radicals. They can besubstituted by 1 to 3 of the following radicals: C₁- to C₆-alkyl, C₁- toC₆-alkoxy, fluoro, chloro, bromo, cyano, hydroxyl, C₁- toC₆-alkoxycarbonyl or nitro. Two adjacent radicals can also form a ring.

The compounds of the formula (I) are known in principle from thenonprior-published German Application No. 19605451.6 and can be preparedas described therein.

Compounds of the formula (I), which as counterion contain theabove-defined anion X⁻ are novel and are likewise a subject of thepresent invention.

Owing to their synthesis, the electrochromic compounds obtained inaccordance with WO 97/30134 of the formula (I), do not carry any anionsX⁻ of the invention. These anions X⁻ have to be introduced by means ofanion exchange. This exchange can take place, for example, in solventsin which the compounds of the formula (I) with the anions originatingfrom their synthesis are of moderate to good solubility but in which thecompounds of the formula (I) with the anions of the invention are ofpoor solubility. The compounds of the formula (I) with the anionsoriginating from their synthesis are then introduced, together withsalts of the anions of the invention, for example the alkali metal saltsor tetraalkylammonium salts listed below under conductive salts, intosuch solvents, and these mixtures are stirred at from room temperatureto the reflux temperature of the solvent, the desired compounds of theformula (I) with the anions of the invention being precipitated andbeing filtered off with suction. Examples of suitable solvents arealcohols such as methanol, ethanol; water; nitrites such asacetonitrile, or mixtures thereof.

Another process involves operating in a two-phase mixture, in which casethe compounds of the formula (I) with the anions originating from theirsynthesis and the alkali metal salts or tetraalkylammonium salts of theanions X⁻ of the invention should be at least partly soluble in onesolvent while the compounds of the formula (I) with the anions X⁻ of theinvention should be readily soluble in the other solvent. This mixtureis then stirred at from room temperature to the reflux temperature ofthe solvent mixture, and is separated. Removal of the second solvent bydistillation gives the compounds of the formula (I) with the anions X⁻of the invention Examples of suitable pairs of solvents arewater/toluene, water/methylene chloride and water/butanone.

A third possibility is the use of ion exchangers.

The electrochromic system of the invention preferably comprises at leastone solvent, resulting in an electrochromic fluid which is likewise asubject of the present invention.

Suitable solvents are all solvents which are redox-inert at the chosenvoltages and which cannot give off electrophiles or nucleophiles orthemselves react as sufficiently strong electrophiles or nucleophilesand so could react with the coloured ionic free radicals. Examples arepropylene carbonate, γ-butyrolactone, acetonitrile, propionitrile,glutaronitrile, methylglutaronitrile, 3,3′-oxydipropionitrile,hydroxypropionitrile, dimethylformamide, N-methylpyrrolidone,sulpholane, 3-methylsulpholane or mixtures thereof. Preference is givento propylene carbonate and to mixtures thereof with glutaronitrile or3-methylsulpholane.

The electrochromic fluid of the invention can include at least one inertconductive salt. It must include a conductive salt if OX₂ is notcationic.

Suitable inert conductive salts are lithium, sodium andtetraalkylammonium salts, especially the latter. The alkyl groups canhave between 1 and 18 C atoms and can be identical or different.Tetrabutylammonium is preferred. Anions of these salts are theabovementioned anions X⁻ in their general, particular or very particulardefinitions.

The conductive salts are preferably employed in the range from 0 to 1molar.

Further possible additives to the electrochromic fluid are thickeners,in order to control the viscosity of the fluid. This may be importantfor controlling the rate of fade after switching off the current.

Suitable thickeners are all compounds usual for these purposes, such aspolyacrylate, polymethacrylate (Luctite L®), polycarbonate andpolyurethane, for example.

The electrochromic fluid can also be in gel form.

Other suitable additives for the electrochromic fluid are UV absorbersto improve the lightfastness. Examples are Uvinul® 3000(2,4-dihydroxybenzophenone, BASF), SANDUVORE® 3035(2-hydroxy-4-n-octyloxybenzophenone, Clariant), Tinuvin® 571(2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, Ciba), Cyasorb 24®(2,2′-dihydroxy-4-methoxybenzophenone, American Cyanamid Company),UVINUL® 3035 (ethyl 2-cyano-3,3-diphenylacrylate, BASF), Uvinul® 3039(2-ethylhexyl 2-cyano-3,3-diphenylacrylate, BASF), UVINUL® 3088(2-ethylhexyl p-methoxycinnamate, BASF), and CHIMASSORB® 90(2-hydroxy-4-methoxy-benzophenone, Ciba).

The UV absorbers are employed in the range from 0.01 to 2 mol/l,preferably from 0.04 to 1 mol/l.

The electrochromic fluid of the invention comprises the substances ofthe formula (I), especially of the formulae (Ia) to (Id), in each casein a concentration of at least 10⁻⁴ mol/l, preferably from 0.001 to 1mol/l. It is also possible to employ mixtures of two or moreelectrochromic substances of the formula (I).

The electrochromic fluids of the invention are eminently suitable as aconstituent of an electrochromic device. A further subject of thepresent invention, accordingly, are electrochromic devices comprising anelectrochromic fluid of the invention. The design of an electrochromicdevice, which may be configured, for example, as a window pane, carsunroof, rearview car mirror or display, is known in principle. Theelectrochromic device of the invention consists of two transparent glassor plastic plates facing one another, of which one may be mirrored, andwhose facing sides have an electroconductive coating of, for example,indium tin oxide (ITO) and between which there is located theelectrochromic fluid of the invention. Other suitable conductivematerials are antimony-doped tin oxide, fluorine-doped tin oxide,antimony-doped zinc oxide, aluminium-doped zinc oxide, tin oxid; andalso conductive organic polymers, such as unsubstituted or substitutedpolythienyls, polypyrroles, polyanilines, polyacetylene. If one of theplates is mirrored, it can also be used as a conductive layer. Thedistance between the two plates is generally 0.005-2 mm, preferably0.02-0.5 mm. The desired distance between the plates is generallyestablished by means of a sealing ring. In the case where theelectrochromic device is an electrochromic display device, at least oneof the two conductive layers, or both, are subdivided into electricallyseparate segments that are contacted individually

Alternatively, it is possible for only one of the two plates to carrythe conductive coating and to be subdivided into segments. Theseparation of the segments can be effected, for example, by means ofmechanical removal of the conductive layer, for example by scoring,scratching, scraping or milling, or chemically, for example by etchingusing, for instance, a solution of FeCl₂ and SnCl₂ in hydrochloric acid.This removal of the conductive layer can be locally controlled by meansof masks, for example photoresistant masks. Also possible, however, isthe production of the electrically separate segments by means ofcontrolled—for example, by means of masks—application—for example,sputtering or printing—of the conductive layer. The contacting of thesegments takes place, for example, by means of fine strips of conductivematerial, by means of which the segment is brought into electricallyconducting communication with a contact at the edge of theelectrochromic device. These fine contact strips can consist either ofthe same material as the conductive layer itself and can be prepared,for example, along with said layer at the same time as it is subdividedinto segments as described above, or alternatively, in order to improvethe conductivity, they can consist of a different material, such as finemetallic conductors made, for example, from copper or silver. Acombination of metallic material and the material of the conductivecoating is a further possibility.

These metallic conductors may, for example, be applied, e.g. bonded, infine wire form, or else may be printed on. All of these above-describedtechniques are common knowledge from the production of liquid-crystaldisplays (LCD).

The displays can be viewed in transmitted light or else reflectively viaa mirror coating.

The two plates are laid atop one another with the conductively coatedand segmented sides facing, separated by means, for example, of asealing ring, and are bonded to one another at the edge. The sealingring may be made, for example, of plastic or thin glass or anothermaterial which is inert with respect to the electrochromic fluid. Thedistance between the plates can also, however, be established by meansof different spacers, for example by means of small plastic or glassbeads or particular fractions of sand, in which case these spacers areapplied together with the adhesive and then together form the sealingring. The seating ring includes one or two cutouts which are used tofill the electrochromic device The distance between the two plates liesbetween 0.005 and 2 mm, and is preferably from 0.02 to 0.5 mm In thecase of large-surface-area display devices, especially those made ofplastic, it may be advantageous to use spacers, for example plasticbeads of equal diameter distributed over the area of the display device,to keep the distance between the plates constant.

This display device is filled with an electrochromic fluid via theapertures in the sealing ring, an operation which must be carried out atall times with exclusion of moisture and oxygen. Filling can be carriedout, for example, by means of fine cannulas or else by the vacuumfilling technique, in which the device and the fluid are placed into ashallow dish and introduced into an evacuable container. This containeris evacuated. Then the display device, which includes only one fillingaperture, is dipped with said aperture into the liquid. When the vacuumis removed, the liquid is then forced into the display device.

When such electrochromic devices are placed upright in the switched-onstate, there is—even after a number of hours or days—no separation ofthe colours of the coloured species formed at the anode and cathode,e.g. OX₁—B—RED₁ and RED₂—B—OX₂. The devices are uniform in colour, showno spotting or striping, and fade rapidly and uniformly after thecurrent is switched off. If, on the other hand, use is made ofelectrochromic compounds of the formula (I) whose anion is not an anionX⁻ of the invention, such as tetrafluoroborate, then after just a shorttime, for example after 1 hour, there is a marked colour separation inthe upright electrochromic device. For example, there is a blue stripeat the top end and a yellow stripe at the bottom end, while in themiddle the expected mixed colour, green, is observed. After the voltageis switched off only the middle zone fades rapidly, whereas the upperand lower zones remain coloured for a relatively long time, for examplefor several hours. The same observation is made in the case ofelectrochromic compounds of the formula (1) whose OX₂ is not cationicand hence there is no anion, and yet which are employed in anelectrochromic fluid whose conductive salt is not an anion of theinvention, e.g. tetrafluoroborate.

In the case of electrochromic display devices, for example segmenteddisplays, when the electrochromic compounds or fluids of the inventionare used, no colour separation within the segment is likewise found,even in the case of long periods of operation in the upright position ofthe device, and there is rapid and complete erasure after the current isswitched off, whereas the use of the abovementioned electrochromicsubstances or fluids not of the invention leads to colour separation andto a very slow erasure of these separated colour regions. Specificallyin the case of display devices it is a frequent occurrence thatindividual segments are switched on for a relatively long period and yetare required to fade rapidly when there is a change in the informationto be displayed. The electrochromic compounds and liquids of theinvention show significant advantages here over those which compriseanions not of the invention.

The self-erasing single-cell electrochromic device of the invention canin addition to the above-described electrochromic substances of theformulae (1), especially of the formulae (Ia) to (Id), also includeother such substances, as are described, for example, in U.S. Pat. No.4,902,108, Topics in Current Chemistry, Vol. 92, pp. 1-44 (1980) andAngew. Chem. 90, 927 (1978). Such electrochromic substances hail, forexample, from the groups indicated above, under the formulae (II) to(XX), in which case none of the radicals listed is able to possess thedefinition “direct bond to the bridge B”. Examples of other suitableelectrochromic substances are tetrazolinium salts or salts or complexesof metal ions, e.g. [Fe(C₅H₅)₂]^(0/1+). The admixture of such redoxsystems may, for example, be advantageous in order to correct the colourin the case of the electrochromic device of the invention, for exampleof the display, in the switched-on state or to render the said colourmore intense.

The anions of such electrochromic co-components are intended to have thedefinition of X⁻ in its abovementioned general, particular and veryparticular definition.

EXAMPLES Example 1

Preparing an Electrochromic Substance of the Formula (I)

a) 5.0 g of 4,4′-bipyridyl were dissolved in 30 ml of an anhydrousacetonitrile at 50° C. At this temperature, 2.7 g of benzyl bromide wereadded dropwise over the course of 50 minutes. After 3 h at 50° C. themixture was cooled and the pale yellow precipitate was filtered off withsuction. It was washed with 60 ml of toluene and dried in vacuo. Thisgave 3.9 g (75% of theory) of the product of the formula

b) 10.1 g of phenothiazine were dissolved at room temperature in 60 mlof anhydrous N-methylpyrrolidone under an N₂ atmosphere. 5.9 g ofpotassium tert-butylate were added. Heating to 30° C. gave an orangesuspension which was stirred at 30° C. for 30 minutes. Then 54 g of1,4-dibromobutane were added in one portion. Upon this addition thetemperature rose to 53° C. The mixture was heated to 70° C. over 45minutes, held at this temperature for 15 minutes and then cooled. Thelight brown suspension was introduced into 1 l of water. It wassubjected to extraction with 3×200 ml of toluene and the extract waswashed with 5×200 ml of water, dried over sodium sulphate andconcentrated on a rotary evaporator. The oily residue was dissolved in400 ml of hexane, insoluble material was removed by filtration, and theremaining solution was concentrated again The excess 1,4-dibromobutanewas then distilled off at from 0.1 to 0.5 mbar. This gave 9.6 g (57% oftheory) of a reddish yellow, viscous oil of the formula

c) 3.7 g of the phenothiazine of the formula (LXV) were dissolved atroom temperature in 10 ml of anhydrous N-methylpyrrolidone under an N₂atmosphere. 1.8 g of the dipyridinium salt of the formula (LXIV) wereadded. The suspension was heated to 80° C. over the course of 1 h andheld at this temperature for a total of 13 h. During this time, thesuspension became increasingly thicker. After the suspension had cooledto room a temperature, it was filtered with suction and the solidproduct was washed with 5 ml of N-methylpyrrolidone. The hygroscopiccrude product of the formula

 with X⁻=Br⁻ was dissolved in 7 ml of methanol and the solution wasfiltered. 3.0 g of sodium cyanotriphenylborate were sprinkled into thefiltrate over the course of 2 h. Slowly, precipitation came about, andwas brought to completion over the course of 18 h of stirring at roomtemperature. Finally, the precipitate was filtered off with suction,washed with methanol until the runoff was colourless, and then dried invacuo. This gave 0.5 g (13% of theory) of pale bluish powder of theformula (LXVI) with X⁻=NC—B(C₆H₅)₃ ⁻.

In an electrochromic device in accordance with Example 29-30 ablueviolet coloration with λ_(max)=517 and 606 nm was obtained

Example 2

a) 9.2 g of phenazine were suspended in 60 ml of anhydroustetrahydrofuran under a nitrogen atmosphere. 30.8 ml of 20% strength byweight phenyllithium solution in 7:3 cyclohexane/diethyl ether wereadded dropwise over the course of 15 minutes, during which thetemperature was held at max. 35° C. The solution was subsequentlystirred at room temperature for 30 minutes.

At 15° C., 30.2 ml of 1,4-dibromobutane were added in one portion. Uponthis addition the temperature rose to 38° C. After 6 h at roomtemperature, 200 ml of water were added and the pH was adjusted to 7.0.The organic phase was separated off, washed three times with 100 ml ofwater each time and concentrated in vacuo. Finally, excess1,4-dibromobutane was distilled off under a pressure of 0.2 mbar. Theoily residue was dissolved hot in 400 ml of ethanol. The productprecipitated on cooling was filtered off with suction, washed withethanol and hexane and dried. This gave 8.0 g (41% of theory) of a paleyellow powder of the 9,10-dihydrophenazine of the formula

b) 7.5 g of the 9,10-dihydrophenazine of the formula (LXVII) from a) and6.1 g of 4,4′-bipyridyl were stirred in 100 ml of acetonitrile at 70° C.under a nitrogen atmosphere for 24 h. After cooling, the mixture wasfiltered with suction and the solid product was washed with 50 ml ofacetone. Drying gave 6.3 g (60% of theory) of the salt of the formula

c) 6.1 g of the salt obtained in b) were stirred in 70 ml ofN-methyl-2-pyrrolidone together with 2.7 ml of benzyl bromide at 70° C.under a nitrogen atmosphere for 7 h. After cooling, the mixture wasdiluted with 150 ml of toluene and the precipitated product was filteredoff with suction. It was washed thoroughly with 150 ml of toluene and500 ml of hexane and dried. This gave 5.5 g (69% of theory) of thedipyridinium salt of the formula

where X⁻=B⁻.

d) 4.0 g of this product from c) were introduced under a nitrogenatmosphere into a two-phase mixture comprising 70 ml of water and 70 mlof toluene. 3.6 g of sodium dodecylbenzenesulphonate were added. Themixture was stirred at 50° C. for 2 h and cooled. During this time, theinitial cloudy mixture became a clear two-phase system. The toluenephase was separated off and concentrated to dryness in vacuo. This gave6.7 g of a sticky, pale greenish product of the formula (LXIX) withX⁻=C₁₂H₂₅—C₆H₄—SO₃ ⁻.

In an electrochromic device in accordance with Example 29-31 a greenishblue coloration with λ_(max)=466 and 407 nm was obtained.

Example 2a (Comparative Example)

4.0 g of this product from Example 2c) were dissolved at 65° C. in 100ml of methanol under a nitrogen atmosphere. 7.4 g of tetrabutylammoniumtetrafluoroborate were sprinkled in over the course of 5 minutes.Precipitation occurred. After 5 minutes at 65° C. the mixture was cooledand the precipitate was filtered off with suction, washed with 200 ml ofmethanol and 50 ml of hexane and dried in vacuo This gave 3.4 g (83% oftheory) of a pale beige powder of the formula (LXIX) with X⁻=BF₄ ⁻.

In an electrochromic device in accordance with Example 29-30 a greenishblue coloration with λ_(max)=466 and 407 nm was obtained.

Example 3

a) 45.3 g of 2-methylthiobenzothiazole were dissolved in 75 ml oftoluene. 151 ml of 1,4-dibromobutane and a spatula tip of potassiumiodide were added. The mixture was boiled for 4 h and then cooled. Itwas filtered, and the solid product was washed with 50 ml of toluene.The filtrate was heated to 50° C., and 35.9 ml of dimethyl sulphate wereadded. This mixture was stirred at 50° C. for 8 h and cooled, and thesolid product was filtered off with suction and washed with 250 ml oftoluene. The product was stirred up in 100 ml of acetone, filtered offwith suction again and washed with 300 ml of acetone. Drying in vacuogave 53.1 g (50% of theory) of the salt of the formula

b) Under a nitrogen atmosphere, 6.95 g of the benzothiazolium salt ofthe formula (LXX) from a) and 2.9 g of the hydrazone of the formula

 (from Aldrich Chemical Company Ltd., England) were suspended in 60 mlof acetonitrile. 2.3 ml of triethylamine were added at room temperature.This briefly produced a solution, after which a precipitate formed.After 5 h at room temperature this precipitate was finally filtered offwith suction, washed with 50 ml of methanol, 100 ml of water and afurther 50 ml of methanol until the runoff was colourless, and was driedin vacuo. This gave 6.0 g (83% of theory) of the azine of the formula

c) Operating as in Example I a) but using 6.8 ml of butyl bromideinstead of benzyl bromide gave 5.2 g (57% of theory) of the pyridiniumsalt of the formula

d) 2.0 g of the azine of the formula (LXXII) from b) and 1.3 g of thepyridinium salt of the formula (LXXIII) from c) were stirred in 20 ml ofN-methyl-2-pyrrolidone at 80° C. under a nitrogen atmosphere for 102 h.After the mixture had cooled, a greenish crystalline product wasfiltered off with suction and washed with 50 ml of acetone. Drying gave0.25 g (7.6% of theory) of the dipyridinium salt of the formula

 with X⁻=Br⁻.

e) 0.25 g of the product from c) was dissolved almost completely in 5 mlof methanol. 0.45 g of sodium cyanotriphenylborate was added. Themixture was stirred at room temperature for 17 h, during which theproduct gradually became crystalline. This product was filtered off withsuction and washed with 25 ml of methanol, 25 ml of water and again with25 ml of methanol. Drying gave 0.15 g (59% of theory) of a pate greypowder of the formula (LXXIV) with X⁻=NC—B(C₆H₅)₃ ⁻.

In an electrochromic device in accordance with Example 29-30 a greencoloration with λ_(max)=402; 606; 734 nm was obtained.

Example 4

a) 4.0 g of the phenothiazine of the formula (LXV) from Example 1b) and0.95 g of 4,4′-bipyridyl were stirred in 10 ml of acetonitrile at 70° C.under a nitrogen atmosphere for 9 h. The suspension was then dilutedwith 10 ml of N-methyl-2-pyrrolidone and was stirred at 70° C. for 25 hand at 80° C. for 7 h. After cooling, the mixture was filtered withsuction and the solid product was washed with 50 ml of methanol anddried in vacuo. This gave 1.6 g (32% of theory) of the dipyridinium saltof the formula

 with X⁻=Br⁻.

b) 1.4 g of the salt of the formula (LXXV) from a) were partly dissolvedin 20 ml of methanol under reflux. 2.5 g of sodium tetraphenylboratewere added. The mixture was boiled for 5 minutes more and then cooledwith stirring. The precipitated product was filtered off with suction,washed with 50 ml of methanol, 50 ml of water and again with 50 ml ofmethanol and dried in vacuo. This gave 1.1 g (77% of theory) of thedipyridinium salt of the formula (LXXV) with X⁻=B(C₆H₅)₄ ⁻.

In an electrochromic device in accordance with Example 29-30 ablueviolet coloration with λ_(max)=517 and 606 nm was obtained.

The examples which follow were prepared in an entirely analogous manner.

MW cagelike Example Colour Anion charge OX₂-B-RED₁ 6

blue-violet 291 − 7

greenish blue 207 −

8

green 133 + 9

green 247 − 10

blue 269 −

11

violet 286 −

12

blue 233 −

13

reddish blue 318.8 − 2 B(C₆H₅)₄ ^(⊖) 14

green 147 + 2 B₉C₂H₁₁CH₃ ^(⊖) 15

violet 302.8 − 2 B_((OC) ₄H₉)₄ ^(⊖) 16

green 267.8 − 2 NC—B(C₆H₅)₃ ^(⊖) 17

green 283 − 2 C₁₇H₃₅COO^(⊖) 18

blue 299 − 2 C₄F₉SO₃ ^(⊖) 19

reddish blue 499 − 2 C₈F₁₇SO₃ ^(⊖) 20

violet 252 −

RED₁-B-OX₂-B-RED₁ 21

greenish blue 319 −

22

blue 133 + 2 B₉C₂H₁₂ ^(⊖) 23

green 325 −

OX₂-B-RED₁-B-OX₂ 24

greenish blue 312 −

RED₁-B-OX₂-B-RED₁ 25

violet 382.8 −

26

green 225 −

27

greenish blue 319 − 4 C₁₇H₃₅—SO₃ ^(⊖) 28

blue-green 225 −

Example 29

A cell as described in U.S. Pat. No. 4,902,108 was constructed from twoglass plates, coated with indium tin oxide (ITO), and a sealing ring.Under a nitrogen atmosphere, this cell was filled by way of an aperturein the sealing ring with a 0.03 molar solution in anhydrousglutaronitrile of the electrochromic substance of the formula (LXXIV)with X^(⊖)=NC—B(C₆H₅)₃ ^(⊖) as in Example 3. The cell was sealed so asto be airtight. The solution in the cell was pale yellow. When a voltageof 1.5 V was applied the solution changed colour rapidly to an intensegreen. When the voltage was switched off, the contents of the celldecoloured fully again within 1 minute. Short-circuiting of the cellresulted in more rapid decolouring.

When the cell was placed upright, the green coloration was still ofuniform intensity over the entire cell area even after operation at 1.5V for 3 h. After being switched off and short-circuited, the celldecoloured rapidly and uniformly over its entire area

Example 30

A cell was constructed as in Example 29. One of the glass plates,however, was mirrored on the side facing away from the ITO coat.

This cell was filled under an N₂ atmosphere with a 0.03 molar solutionin anhydrous propylene carbonate of the electrochromic substance of theformula (LXIX) with X^(⊖)=C₁₂H₂₅—C₆H₄—SO₃ ^(⊖) as in Example 2. Thecolour of the solution in the cell was pale yellow. When a voltage of0.9 V was applied the solution changed colour rapidly to a deep greenishblue; after the supply of current had been switched off and the cellshort-circuited, the contents of the cell decoloured again within about10 s to give the original pale yellow. More than 100,000 such operatingcycles were survived without any changes whatsoever.

When the cell was placed upright, the green coloration was still ofuniform intensity over the entire cell area even after operation at 1.5V for 3 days. After being switched off and short-circuited, the celldecoloured uniformly in the course of 10 s over its entire area.

Example 30a (Comparative Example)

The procedure as described in Example 30 was followed but using theelectrochromic substance of the formula (LXIX) with X⁻=BF₄ ⁻ as inExample 2a. The colour of the solution in the cell was pale yellow. Whena voltage of 0.9 V was applied the solution changed colour rapidly to adeep greenish blue; after the supply of current had been switched offand the cell short-circuited, the contents of the cell decoloured againwithin 10 s to give the original pale yellow. More than 100,000 suchoperating cycles were survived without any changes whatsoever.

When the cell was placed upright, within just 1 h a blue stripe wasformed at the upper edge of the cell and a greenish yellow stripe at thelower edge of the cell, while the central zone of the cell remainedblue. This state was maintained even throughout the course of prolongedoperation. The two stripes each made up about ¼ of the vertical heightof the cell. After being switched off and short-circuited, the celldecoloured in the course of 10 s in the central zone of the cell. Theblue and greenish yellow stripes at the top and bottom, respectively,however, remained. Only after 2-3 h had these stripes too returnedcompletely to their pale coloration.

Example 31

An ITO-coated glass plate was sprayed on the coated side with acommercial photoresist, such as Positiv.20 from Kontakt Chemie,Iffezheim and dried in the dark at 50 to 70° C. for 1 h. The resist coatwas then covered with a film containing—as shown in FIG. 1—blacksegments in a transparent surround. This film was printed with a laserprinter to a computer-produced original. The photoresist coat was thenexposed through this film to Uv light (from a mercury lamp, e.g. HBO 200W/2 from Osram or from a high-pressure xenon lamp XBO 75 W/2 from Osram)for 1 to 5 minutes. The film was removed and the resist coat was treatedin a bath of caustic soda (7 g of sodium hydroxide per liter of water)so that the exposed areas were rinsed away. The pretreated glass platewas then placed in a bath of 67 g of FeCl₂×4 H₂O, 6 g of SnCl₂×2 H₂O,104 ml of water and 113 ml of 37 per cent by weight hydrochloric acid,thereby removing the ITO coat at the resist-free, formerly exposedareas. The remaining resist coat was removed with acetone. This gave aglass plate (1) bearing segments (4), conductor connections (3) andcontacts (2).

A rectangular ring was cut out from a 0.2 mm thick polyethylene film. Asection about 1-2 cm long was removed (5) from one of its long sides.This film was then placed onto the ITO-coated side of a second glassplate (7). On the outside of the film—with the exception of the aperture(6)—there was applied a two-component adhesive, for example UHU® plusendfest 300 from UHU GmbHK Bühl in Baden. The etched glass plate (1)prepared as described above was then placed onto the film in such a waythat the ITO coat lay on the side of the film (see FIG. 2). Thetwo-component adhesive was then cured, if appropriate by gentle heatingto about 40° C.

The cell was then filled under a nitrogen or argon atmosphere with asolution of 220 mg of the electrochromic compound of the formula

in 10 ml of anhydrous propylene carbonate, which had been prepared undera nitrogen or argon atmosphere, by way of the aperture (6), using, forexample, a fine pipette or using vacuum to draw in the solution. Thefilling aperture (6) was then filled with a matching piece ofpolyethylene film and sealed tightly with two-component adhesive.

Applying a voltage of 0.8 V to the contacts (2) of the segments, as thecathode, and to the nonetched second plate (7), as the anode, resultedin rapid development of a deep greenish blue image of the contactedsegments. In this way it was possible to generate all letters andnumerals which can be depicted by means of seven segments, in a deepgreenish blue on a pale yellow background. Switching off the voltage andshort-circuiting the contacts caused the image to disappear againrapidly.

When this cell was placed upright, the connected segments remained asingle colour, without any different-coloured edge stripes whatsoever,even after several hours of operation. After switching off the voltageand short-circuiting the contacts, the segments decoloured rapidly anduniformly.

In full analogy with Examples 29-31, electrochromic cells wereconstructed using the electrochromic substances set out in Examples1-28, with similarly good results.

What is claimed is:
 1. An electrochromic system comprising a weaklycolored or colorless combination of at least one oxidizable substanceRED₁ that releases electrons at an anode and in so doing undergoestransition into a substance OX₁ and at least one reducible substance OX₂that accepts electrons at a cathode and in so doing undergoes transitioninto a substance RED₂, with the proviso that at least one of OX₁ or RED₂is accompanied by an increase in the absorbance in the visible region ofthe spectrum and thereby becomes colored and the combination is restoredto the weakly colored or colorless form after charge equalization,wherein (1) at least one of the substances RED₁ is linked covalently toat least one of the substances OX₂ by a bridge, and (2) at least oneanion X⁻ having (a) a molar mass greater than 200 g/mol and/or (b) acagelike structure is present.
 2. An electrochromic system according toclaim 1 wherein the anion X⁻ is the counterion of the reduciblesubstance OX₂ and/or a constituent of an inert conductive salt.
 3. Anelectrochromic system according to claim 1 wherein the reduciblesubstance OX₂ has no positive charge and the anion X⁻ is a constituentof an inert conductive salt.
 4. An electrochromic system according toclaim 1 wherein the anion X⁻ is C₁₀-C₂₅-alkanesulphonate;C₅-C₁₈-perfluoroalkanesulphonate; C₁₃-C₂₅-alkanoate; benzenesulphonatesubstituted by nitro, C₄-C₂₅-alkyl, perfluoro-C₁-C₈-alkyl,C₁-C₁₂-alkoxycarbonyl, or dichloro; naphthalenesulphonate orbiphenylsulphonate, each of which is unsubstituted or substituted bynitro, cyano, hydroxyl, C₁-C₂₅-alkyl, C₁-C₁₂-alkoxy, amino,C₁-C₁₂-alkoxycarbonyl, or chloro; benzenesulphonate,naphthalene-sulphonate, or biphenyldisulphonate, each of which isunsubstituted or substituted by nitro, cyano, hydroxyl, C₁-C₂₅-alkyl,C₁-C₁₂-alkoxy, C₁-C₁₂-alkoxycarbonyl or chloro; benzoate substituted bydinitro, C₆-C₂₅-alkyl, C₄-C₁₂-alkoxycarbonyl, benzoyl, chlorobenzoyl, ortoluoyl; the anion of naphthalenedicarboxylic acid; diphenyl etherdisulphonate; tetraphenylborate; cyanotriphenylborate,tetra-C₃-C₂₀-alkoxyborate; tetraphenoxyborate; 7,8- or7,9-dicarba-nido-undecaborate(1-) or (2-), each of which isunsubstituted or substituted on the B and/or C atoms by one or twoC₁-C₁₂-alkyl or phenyl groups; dodecahydrodicarbadodecaborate(2-); orB—C₁-C₁₂-alkyl-C-phenyl-dodecahydrodicarbadodecaborate (1-).
 5. Anelectrochromic system according to claim 1 comprising at least oneelectrochromic substance of formula (I)YB—Z_(a)B—Y_(b)_(c)B—Z  (I), wherein Y and Z independently of oneanother represent a radical OX₂ or RED₁, subject to the proviso that atleast one Y represents OX₂ and at least one Z represents RED₁,  whereinOX₂ represents the radical of a reversibly electrochemically reducibleredox system, and RED₁ represents the radical of a reversiblyelectrochemically oxidizable redox system, B represents a bridge, crepresents an integer from 0 to 5, and a and b independently of oneanother represent an integer from 0 to
 5. 6. An electrochromic systemaccording to claim 5 wherein in formula (I) Y represents OX₂ and Zrepresents RED₁ and Y and Z alternate in their sequence.
 7. Anelectrochromic system according to claim 1 comprising at least oneelectrochromic substance of the formulas OX₂—B—RED₁  (Ia),OX₂—B—RED₁—B—OX₂  (Ib), RED₁—B—OX₂—B—RED₁  (Ic), orOX₂—(B—RED₁—B—OX₂)_(d)—B—RED₁  (Id), wherein OX₂ represents the radicalof a reversibly electrochemically reducible redox system, RED₁represents the radical of a reversibly electrochemically oxidizableredox system, B represents a bridge, and d represents an integer from 1to
 5. 8. An electrochromic system according to claim 1 comprising atleast one electrochromic substance of the formulas OX₂—B—RED₁  (Ia),OX₂—B—RED₁—B—OX₂  (Ib), RED₁—B—OX₂—B—RED₁  (Ic), orOX₂—(B—RED₁—B—OX₂)_(d)—B—RED₁  (Id), wherein OX₂ represents the radicalof a cathodically reducible substance which in its cyclic voltammogram,recorded in an inert solvent at room temperature, exhibits at least twochemically reversible reduction waves, the first of said reduction wavesleading to an increase in the absorbance at at least one wavelength inthe visible region of the electromagnetic spectrum, RED₁ represents theradical of an anodically reversibly oxidizable substance which in itscyclic voltammogram, recorded in an inert solvent at room temperature,exhibits at least two chemically reversible oxidation waves, the firstof said oxidation waves leading to an increase in the absorbance at atleast one wavelength in the visible region of the electromagneticspectrum, B represents a bridge, and d represents an integer from 1 to5.
 9. An electrochromic system according to claim 1 comprising at leastone electrochromic substance of the formulas OX₂—B—RED₁  (Ia), OX₂—B—RED₁—B—OX₂  (Ib), RED₁—B—OX₂—B—RED₁  (Ic), or OX₂—(B—RED₁—B—OX₂)_(d)—B—RED₁  (Id), wherein OX₂ represents a radical of the formulas

 wherein R², R³, R⁴, R⁵, R⁸, R⁹, R¹⁶, R¹⁷, R¹⁸, and R¹⁹ independently ofone another denote C₁-C₁₈-alkyl, C₂-C₁₂-alkenyl, C₃-C₇-cycloalkyl,C₇-₁₅-aralkyl, or C₆-C₁₀-aryl, or R⁴ and R⁵ together or R⁸ and R⁹together form a —(CH₂)₂— or —(CH₂)₃— bridge, R⁶, R⁷, R²², R²³, R²⁴, andR²⁵ independently of one another denote hydrogen, C₁-C₄-alkyl,C₁-C₄-alkoxy, halogen, cyano, nitro, or C₁-C₄-alkoxy-carbonyl, or R²²and R²³ together and/or R²⁴ and R²⁵ together form a —CH═CH—CH═CH—bridge, R¹⁰ and R¹¹; R¹² and R¹³; and R¹⁴ and R¹⁵ independently of oneanother denote hydrogen or in pairs denote a —(CH₂)₂—, —(CH₂)₃—, or—CH═CH— bridge, R⁶⁹ to R⁷⁴ independently of one another denote hydrogenor C₁-C₆-alkyl, or R⁶⁹ and R¹² together and/or R⁷⁰ and R¹³ together forma —CH═CH—CH═CH— bridge, R²⁰ and R²¹ independently of one another denoteO, N—CN, C(CN)₂, or N—C₆-C₁₀-aryl, R²⁶ denotes hydrogen, C₁-C₄-alkyl,C₁- to C₄-alkoxy, halogen, cyano, nitro, C₁-C₄-alkoxycarbonyl, orC₆-C₁₀-aryl, E¹ and E² independently of one another denote O, S, NR¹, orC(CH₃)₂, or E¹ and E² together form an N—(CH₂)₂—N bridge, R¹ denotesC₁-C₁₈-alkyl, C₂-C₁₂-alkenyl, C₄-C₇-cycloalkyl, C₇-C₁₅-aralkyl, orC₆-C₁₀-aryl, Z¹ denotes a direct bond, —CH═CH—, —C(CH₃)═CH—, —C(CN)═CH—,—CCl═CCl—, —C(OH)═CH—, —CCl═CH—, —C≡C—, —CH═N—N═CH—,—C(CH₃)═N—N═C(CH₃)—, or —CCl═N—N═CCl—, Z² denotes —(CH₂)_(r)— or—CH₂—C₆H₄—CH₂—, r denotes an integer from 1 to 10, and X⁻ denotes ananion that is redox-inert under the conditions in which theelectrochromic system is used and (a) a molar mass greater than 200g/mol and/or (b) a cagelike structure is present, wherein the bond tobridge B is via one of the radicals R² to R¹⁹ or R²² to R²⁷ or, if E¹ orE² represents NR¹, is via the radical R¹, said radicals representing adirect bond to bridge B, RED₁ represents a radical of the formulas

 wherein R²⁸R²⁹, R³⁰, R³¹, R³⁴, R³⁵, R³⁸, R³⁹, R⁴⁶, R⁵³, and R⁵⁴independently of one another denote C₁-C₁₀-alkyl, C₂-C₁₂alkenyl,C₃-C₇-cycloalkly, C₇-C₁₅-aralkyl, or C₆-C₁₀-aryl, and R⁴⁶, R⁵³, and R⁵⁴additionally denote hydrogen, R³², R³³, R³⁶, R³⁷, R⁴⁰, R⁴¹, R⁴² to R⁴⁵,R⁴⁷, R⁴⁸, R⁴⁹, R⁵⁰, R⁵¹, R⁵², R⁵⁵, R⁵⁶, and R⁵⁷ independently of oneanother denote hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, halogen, cyano,nitro, C₁-C₄-alkoxycarbonyl, or C₆-C₁₀-aryl, and R⁵⁷ and R⁵⁸additionally denote an optionally benzo-fused aromatic or quasiaromaticfive- or six-membered heterocyclic ring and R⁴⁸ additionally denotesNR⁷⁵R⁷⁶, R⁴⁹ and R⁵⁰ together and/or R⁵¹ and R⁵² together form a—(CH₂)₃—, —(CH₂)₄—, —(CH₂)₅—, or —CH═CH—CH═CH— bridge, Z³ denotes adirect bond or a —CH═CH— or —N═N— bridge, ═Z⁴═ denotes a direct doublebond or a ═CH—CH═ or ═N—N═ bridge, E³, E⁴, E⁵, E¹⁰, and E¹¹independently of one another denote O, S, NR⁵⁹, or C(CH₃)₂, and E⁵additionally denotes C═O or SO₂, or E³ and E⁴ independently of oneanother denote —CH═CH—, E⁶ to E⁹ independently of one another denote S,Se, or NR⁵⁹, R⁵⁹, R⁷⁵, and R⁷⁶ independently of one another denoteC₁-C₁₂-alkyl, C₂-C₈-alkenyl, C₃-C₇-cycloalkyl, C₇-C₁₅-aralkyl, orC₆-C₁₀-aryl, and R⁷⁵ additionally denotes hydrogen, or R⁷⁵ and R⁷⁶ inthe definition of NR⁷⁵R⁷⁶ form, together with the N atom to which theyare attached, a five- or six-membered, saturated ring that can containfurther heteroatoms, R⁶¹ to R⁶⁸ independently of one another denotehydrogen, C₁-C₆-alkyl, C₁-C₄-alkoxy, cyano, C₁-C₄-alkoxycarbonyl, orC₆-C₁₀-aryl, or R⁶¹ and R⁶² together and R⁶⁷ and R⁶⁸ togetherindependently form a —(CH₂)₃—, —(CH₂)₄—, or —CH═CH—CH═CH— bridge, and vdenotes an integer between 0 and 10, wherein the bond to bridge B is viaone of the radicals R²⁸ to R⁵⁸, R⁶¹, R⁶², R⁶⁷, or R⁶⁸ or, if one of theradicals E³ to E¹¹ represents NR⁵⁹, is via the radical R⁵⁹, saidradicals representing a direct bond to bridge B, B represents a bridgeof the formula —(CH₂)_(n)— or —[Y¹ _(s) (CH₂)_(m)—Y²]_(o)—(CH₂)_(p)—Y³_(q)—, each such bridge being unsubstituted or substituted byC₁-C₄-alkoxy, halogen, or phenyl,  wherein Y¹, Y², and Y³ independentlyof one another represent O, S, NR⁶⁰, COO, CONH, NHCONH,cyclopentanediyl, cyclohexanediyl, phenylene, or naphthylene, R⁶⁰denotes C₁-C₆-alkyl, C₂-C₆-alkenyl, C₄-C₇-cycloalkyl, C₇-C, ₁₅-aralkyl,or C₆-C₁₀-aryl, n denotes an integer from 1 to 12, m and p independentlyof one another denote an integer from 0 to 8, o denotes an integer from0 to 6, and q and s independently of one another denote 0 or 1, and drepresents an integer from 1 to 5, wherein if the reducible substanceOX₂ has no positive charge, then anion X⁻ is a constituent of an inertconductive salt.
 10. An electrochromic system according to claim 1comprising at least one electrochromic substance of the formulasOX₂—B—RED₁  (Ia), OX₂—B—RED₁—B—OX₂  (Ib), RED₁—B—OX₂—B—RED₁  (Ic), orOX₂—(B—RED₁—B—OX₂)_(d)—B—RED₁  (Id), wherein OX₂ represents a radical ofthe formulas

 wherein R², R³, R⁴, R⁵, R⁸, and R⁹ independently of one anotherrepresent C₁-C₁₂-alkyl, C₂-C₈-alkenyl, C₅-C₇-cycloalkyl, C₇-C₁₅-aralkyl,or C₆-C₁₀-aryl, R⁶ and R⁷ independently of one another representhydrogen, methyl, ethyl, methoxy, ethoxy, fluoro, chloro, bromo, cyano,nitro, methoxycarbonyl, or ethoxycarbonyl, R¹⁰ and R¹¹; R¹² and R¹³; andR¹⁴ and R¹⁵ independently of one another denote hydrogen or, if Z¹denotes a direct bond, in pairs denote a —(CH₂)₂—, —(CH₂)₃—, or —CH═CH—bridge, or R⁴ and R⁵ and R⁸ and R⁹ independently of one another in pairstogether represent a —(CH₂)₂— or —(CH₂)₃— bridge if Z¹ denotes a directbond, R⁶⁹ to R⁷⁴ independently of one another denote hydrogen orC₁-C₄-alkyl, E¹ and E² are identical and represent O, S, NR¹, or C(CH₃)₂or together form an N—(CH₂)₂—N bridge, R¹ represents C₁-C₁₂-alkyl,C₂-C₄-alkenyl, C₅-C₇-cycloalkyl, C₇-C₁₅-aralkyl, or C₆-C₁₀-aryl, Z¹represents a direct bond, —CH═CH—, —C(CH₃)═CH—, —C(CN)═C—, —C≡C—, or—CH═N—N═CH—, Z² represents —(CH)_(r)— or —CH₂-C₆H₄-CH₂—, r represents aninteger between 1 and 6, X⁻ represents C₁₀-C₂₅-alkanesulphonate;C₅-C₁₈-perfluoroalkanesulphonate; C₁₃-C₂₅-alkanoate; benzenesulphonatesubstituted by nitro, C₄-C₂₅-alkyl, perfluoro-C₁-C₈-alkyl,C₁-C₁₂-alkoxycarbonyl, or dichloro; naphthalenesulphonate orbiphenylsulphonate, each of which is unsubstituted or substituted bynitro, cyano, hydroxyl, C₁-C₂₅-alkyl, C₁-C₁₂-alkoxy, amino,C₁-C₁₂-alkoxycarbonyl, or chloro; benzenesulphonate,naphthalenesulphonate, or biphenyldisulphonate, each of which isunsubstituted or substituted by nitro, cyano, hydroxyl, C₁-C₂₅-alkyl,C₁-C₁₂-alkoxy, C₁-C₁₂-alkoxycarbonyl or chloro; benzoate substituted bydinitro, C₆-C₂₅-alkyl, C₄-C₁₂-alkoxycarbonyl, benzoyl, chlorobenzoyl, ortoluoyl; the anion of naphthalenedicarboxylic acid; diphenyl etherdisulphonate; tetraphenylborate; cyanotriphenylborate,tetra-C₃-C₂₀-alkoxyborate; tetraphenoxyborate; 7,8- or7,9-dicarba-nido-undecaborate(1-) or (2-), each of which isunsubstituted or substituted on the B and/or C atoms by one or twoC₁-C₁₂-alkyl or phenyl groups; dodecahydrodicarbadodecaborate(2-); orB—C₁-C₁₂-alkyl-C-phenyl-dodecahydrodicarbadodecaborate(1-), wherein thebond to bridge B is via one of the radicals R² to R¹¹ or, if E¹ or E²represents NR¹, is via the radical R¹, said radicals representing adirect bond to bridge B, RED₁ represents a radical of the formulas

 wherein R²⁸, R²⁹, R³⁰, R³¹, R³⁴, R³⁵, R³⁸, R³⁹, R⁴⁶, R⁵³, and R⁵⁴independently of one another denote C₁-C₁₂-alkyl, C₂-C₈-alkenyl,C₅-C₇-cycloalkyl, C₇-C₁₅-aralkyl, or C₆-C₁₀-aryl, and R⁴⁶, R⁵³ and R⁵⁴additionally denote hydrogen, R³², R³³, R³⁶, R³⁷, R⁴⁰, R⁴¹, R⁴⁷, R⁴⁸,R⁴⁹, R⁵⁰, R⁵¹, R⁵², R⁵⁵, and R⁵⁶ independently of one another denotehydrogen, methyl, ethyl, methoxy, ethoxy, fluoro, chloro, bromo, cyano,nitro, methoxycarbonyl, ethoxycarbonyl, or phenyl, and R⁵⁷ and R⁵⁸additionally denote 2- or 4-pyridyl, and R⁴⁸ additionally denotesNR⁷⁵R⁷⁶, Z³ denotes a direct bond or a —CH═CH— or —N═N— bridge, ═Z⁴═denotes a direct double bond or a ═CH—CH═ or ═N—N═ bridge, E³, E⁴, E⁵,E¹⁰, and E¹¹, independently of one another denote O, S, NR⁵⁹, orC(CH₃)₂, with the proviso that E³ and E⁴ have the same meaning, E⁶ to E⁹are identical to one another and denote S, Se, or NR⁵⁹, and E⁵additionally denotes C═O, E⁶ represents NR⁵⁹, where R⁵⁹ denotes a directbond to the bridge B, and E⁷ to E⁹ denote S, Se, or NR⁵⁹ but need not beidentical to one another, R⁵⁹, R⁷⁵, and R⁷⁶ independently of one anotherdenote C₁-C₁₂-alkyl, C₂-C₈-alkenyl, C₅-C₇-cycloalkyl, C₇-C₁₅-aralkyl, orC₆- to C₁₀-aryl, and R⁷⁵ additionally denotes hydrogen, or R⁷⁵ and R⁷⁶in the definition of NR⁷⁵R⁷⁶ form, together with the N atom to whichthey are attached, pyrrolidino, piperidino or morpholino, R⁶¹ and R⁶²and R⁶⁷ and R⁶⁸ independently of one another represent hydrogen,C₁-C₄-alkyl, methoxycarbonyl, ethoxycarbonyl or phenyl, or in pairstogether represent a —(CH₂)₃— or —(CH₂)₄— bridge, R⁶³ to R⁶⁶ representhydrogen, and v represents an integer from 1 to 6, wherein the bond tothe bridge B is via one of the radicals R²⁸ to R⁴¹, R⁴⁶ to R⁵⁶, R⁶¹,R⁶², R⁶⁷, or R⁶⁸ or, if one of the radicals E³-E¹¹ represents NR⁵⁹, isvia the radical R⁵⁹, said radicals representing a direct bond to bridgeB, represents a bridge of the formulas —(CH₂)_(n)—,—(CH₂)_(m)—O—(CH₂)_(p)—, —(CH)_(m)—NR⁶⁰—(CH₂)_(p)—,—(CH₂)_(m)—C₆H₄—(CH₂)_(p)—[O—(CH₂)_(p)]_(o)—O——[NR⁶⁰—(CH₂)_(p)]_(o)—NR⁶⁰—,—[C₆H₄—(CH₂)_(p)]_(o)—C₆H₄—, —(CH₂)_(m)—OCO—C₆H₄—COO—(CH₂)_(p)—,—(CH₂)_(m)—NHCO—C₆H₄—CONH—(CH₂)_(p)—,—(CH₂)_(m)—NHCONH—C₆H₄—NHCONH—(CH₂)_(p)—,—(CH₂)_(m)—OCO—(CH₂)_(t)—COO—(CH₂)—,—(CH₂)_(m)—NHCO—(CH₂)_(t)—CONH—(CH)_(p)—, or—(CH₂)_(m)—NHCONH—(CH₂)_(t)—NHCONH—(CH₂)_(p)—, wherein R⁶⁰ representsmethyl, ethyl, benzyl, or phenyl, n represents an integer from 1 to 10,m and p independently of one another represent an integer from 0 to 4, orepresents an integer from 0 to 2, and t represents an integer from 1 to6, and d represents an integer from 1 to
 5. 11. An electrochromic systemaccording to claim 1 comprising at least one electrochromic substance ofthe formulas OX₂—B—RED₁  (Ia), OX₂—B—RED₁—B—OX₂  (Ib), RED₁—B—OX₂—B—RED₁  (Ic), or OX₂—(B—RED₁—B—OX₂)_(d)—B—RED₁  (Id),wherein OX₂ represents a radical of the formulas

 wherein R², R⁴, and R⁸ represent a direct bond to the bridge B, R³, R⁵,and R⁹ independently of one another represent methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl, octyl, benzyl or phenyl, or R³, R⁵, and R⁹in compounds of the formulas (Ic) or (Id) also represent a direct bondto the bridge B, R⁶ and R⁷ are identical and represent hydrogen, methyl,methoxy, chloro, cyano, or methoxycarbonyl, R¹⁰ and R¹¹; R¹² and R¹³;and R¹⁴ and R¹⁵ independently of one another represent hydrogen or, ifZ¹ denotes a direct bond, in pairs represent a —CH═CH— bridge, R⁶⁹ toR⁷² are identical and denote hydrogen, methyl, or ethyl, R⁷³ and R⁷⁴denote hydrogen, E¹ and E² are identical and represent O or S, Z¹represents a direct bond or —CH═CH—, X⁻ representsC₁₅-C₂₂-alkanesulphonate, C₈-C₁₂-perfluoroalkanesulphonate,nitrobenzenesulphonate, dinitrobenzenesulphonate, mono- orbis-C₄-C₁₂-alkylbenzenesulphonate, dichlorobenzenesulphonate,naphthalenesulphonate, nitronaphthalenesulphonate,dinitronaphthalenesulphonate, mono- orbis-C₃-C₁₂-alkylnaphthalenesulphonate, hydroxynaphthalenesulphonate,aminonaphthalenesulphonate, biphenylsulphonate, benzenedisulphonate,nitrobenzenedisulphonate, C₄-C₁₂-alkylbenzenedisulphonate,naphthalenedisulphonate, nitronaphthalenedisulphonate,C₄-C₁₂-alkylnaphthalenedisulphonate, biphenyldisulphonate,dinitrobenzoate, mono- or bis-C₈-C₁₂-alkylbenzoate,C₆-C₁₂-alkoxycarbonylbenzoate, benzylbenzoate, toluoylbenzoate, theanion of naphthalenedicarboxylic acid, cyanotriphenylborate,tetra-C₄-C₁₂-alkoxyborate, tetraphenoxyborate, 7,8- or7,9-dicarba-nido-undecaborate(1-) or (2-), each of which isunsubstituted or substituted on the B and/or C atoms by one or twomethyl, ethyl, butyl, or phenyl groups,dodecahydrodicarbadodecaborate(2-) orB-methyl-C-phenyl-dodecahydrodicarbadodecaborate(1-), with the provisothat for polyvalent anions X⁻ represents one equivalent of the anion,RED₁ represents a radical of the formulas

 wherein R²⁸, R³⁴, R³⁸, R⁴⁶, and R⁴⁹ represent a direct bond to thebridge B, R²⁹, R³⁰, R³¹, R³⁵, and R³⁹ independently of one anotherrepresent methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,benzyl or phenyl, or, in compounds of the formula (Ib) or (Ic), R³⁰,R³⁵, and R³⁹ also represent a direct bond to the bridge B, R³², R⁴⁷, andR⁴⁸ represent hydrogen, R³⁶, R³⁷, R⁴⁰, R⁴¹ and R⁵⁰ to R⁵² independentlyof one another represent hydrogen, methyl, methoxy, chloro, cyano,methoxycarbonyl, or phenyl, or, in compounds of the formula (Ib) or(Id), R⁵¹ also represents a direct bond to the bridge B, Z³ represents adirect bond or a —CH═CH— or —N═N— bridge, ═Z⁴═ represents a directdouble bond or a ═CH—CH═ or ═N—N═ bridge, E³ to E⁵ independently of oneanother represent O, S, or NR⁵⁹, with the proviso that E³ and E⁴ havethe same meaning, E⁶ to E⁹ are identical to one another and represent S,Se, or NR⁵⁹, R⁵⁹ represents methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, benzyl, or phenyl, or, in formula (XVI) of compounds offormula (Ib) or (Id), also represents a direct bond to the bridge B, Brepresents a bridge of the formulas —(CH₂)_(n)—, (CH₂)_(m)—O—(CH₂)_(p)—,—(CH₂)_(m)—NR⁶⁰—(CH₂)_(p)—, —(CH₂)_(m)—C₆H₄—(CH₂)_(p)—, —O—(CH₂)_(p)—O—,—NR⁶⁰—(CH₂)_(p)—NR⁶⁰—, —(CH₂)_(m)—OCO—C₆H₄—COO—(CH₂)_(p)—,—(CH₂)_(m)—NHCO—C₆H₄—CONH—(CH₂)_(p)—,—(CH₂)_(m)—NHCONH—C₆H₄—NHCONH—(CH₂)_(p)—,—(CH₂)_(m)—OCO—(CH₂)_(t)—COO—(CH₂)_(p)—,—(CH₂)_(m)—NHCO—(CH₂)_(t)—CONH—(CH₂)_(p)—, or—(CH₂)_(m)—NHCONH—(CH₂)_(t)—NHCONH—(CH₂)_(p)—, wherein R⁶⁰ representsmethyl, n represents an integer from 1 to 10, m and p are identical andrepresent an integer from 0 to 2, and t represents an integer from 1 to6, and d represents an integer from 1 to
 5. 12. An electrochromic systemaccording to claim 1 comprising at least one electrochromic substance ofthe formulas

wherein R³, R⁵, R³⁵, and R³⁹ independently of one another representmethyl, ethyl, propyl, butyl, pentyl, hexyl, or benzyl, R⁶ and R⁷ andR³⁶ and R³⁷ in pairs are identical and represent hydrogen, methyl,methoxy, chloro, cyano, or methoxycarbonyl, R¹² and R¹³ representhydrogen or, if Z¹ denotes a direct bond, together represent a —CH═CH—bridge, R⁶⁹ to R⁷² are identical and represent hydrogen or methyl, E¹and E² are identical and represent O or S, Z¹ represents a direct bondor —CH═CH—, R³², R⁴⁷, and R⁴⁸ represent hydrogen, E³, E⁴, and E⁵independently of one another represent O, S, or NR⁵⁹, with the provisothat E³ and E⁴ are identical, R²⁹, R³⁰, and R³¹ and R⁵⁹ independently ofone another represent methyl, ethyl, propyl, butyl, pentyl, hexyl, orbenzyl, R⁴⁰ and R⁴¹ are identical and represent hydrogen, methyl, ethyl,propyl, butyl, or phenyl, Z³ represents a direct bond, —CH═CH—, or—N═N—, R⁵⁰ to R⁵² independently of one another represent hydrogen,methyl, methoxy, chloro, cyano, methoxycarbonyl, ethoxycarbonyl, orphenyl, E⁶ to E⁹ are identical to one another and represent S, Se, orNR⁵⁹, Z⁴ represents a direct double bond or a ═CH—CH═ or ═N—N═ bridge, mrepresents an integer from 1 to 5, u represents 0 or 1, and X⁻represents C₁₅-C₂₀-alkanesulphonate, C₅-C₈-perfluoroalkanesulphonate,mono- or dibutylbenzenesulphonate, mono- ordi-tert-butylbenzenesulphonate, octylbenzenesulphonate,dodecylbenzenesulphonate, naphthalenesulphonate, biphenylsulphonate,nitrobenzenedisulphonate, naphthalenedisulphonate,dibutylnaphthalenesulphonate, biphenyldisulphonate, benzoylbenzoate,cyanotriphenylborate, tetra-C₃- to C₈-alkoxyborate, tetraphenoxyborate,7,8- or 7,9-dicarba-nido-undecaborate(1-) or (2-) ordodecahydrodicarbadodecaborate(2-), with the proviso that for polyvalentanions X⁻ represents one equivalent of the anion.